In the meat packing industry standard common practice is to suspend cattle or sheep in an upside down position and to then close off the weasand, the tube (also know as the oesophagus) connecting the throat of the animal to its stomach or paunch. The weasand is closed off to prevent the contents of the stomach, or ingesta, from causing contamination from leakage of the stomach contents once the weasand is cut.
A common practice for closing off the weasand includes use of a tool called a rodder which is used to push the weasand clip to the closed or sealed position. In use, the rodder slips around the outside of the weasand and then two strokes of the rodder are required. The first stroke is necessary for the rodder to cut the sinews or membranes attached to the outside of the weasand to clear the way for the second step of moving the clip to the sealed position. After the first stroke the rodder is retracted, and the clip is then locked around the weasand in front of the rodder prior to the second stroke in which the clip is moved to the sealed position.
One weasand clip commonly used today comprises a flexible plastic split ring made by ADEPT Limited of Auckland, New Zealand. This weasand clip has a generally C-shaped base with flexible teeth projecting into the interior of the clip. When the ends of the clip are locked around the weasand, the flexible teeth apply pressure to seal off the weasand. After the first stroke of the rodder is used to clear the vicinity of the weasand, the second stroke of the rodder is used to force the closed ring up along the length of the weasand. The flexible teeth maintain a sliding seal when the ring is pushed along the weasand to the closed or sealed position in the vicinity of the stomach or paunch. The sliding seal provided by the locked weasand clip pushes any ingesta contained in the weasand back into the stomach of the animal.
The present invention is based on the recognition that a properly structured weasand clip can be used to cut the sinews or membranes along the length of the weasand while at the same time maintaining a sliding seal as the clip is pushed up along the length of the weasand by the rodder. Thus, only a single stroke of the rodder is necessary to clear the weasand-attached sinews and move the weasand clip to the sealed or closed position once the weasand is initially exposed. By reducing the amount of work required to seal off the weasand, worker fatigue is greatly reduced and production rate is increased.
The present invention is also based on the recognition that the weasand clip must be strong enough to both clear the weasand area while at the same time maintaining a reliable seal in a single stroke of the rodder, without structural failure to the weasand clip. A weasand clip made from a strong plastic material may be unsuitable since it can be brittle and prone to cracking or other fatigue failure.